Impact of an Atoms-First Approach on Student ... - ACS Publications

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Cite This: J. Chem. Educ. XXXX, XXX, XXX−XXX

Impact of an Atoms-First Approach on Student Outcomes in a TwoSemester General Chemistry Course George Chitiyo,‡ Darek W. Potter,‡ and Chad E. Rezsnyak*,† †

Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee 38505, United States Department of Curriculum & Instruction, Tennessee Technological University, Cookeville, Tennessee 38505, United States

‡

J. Chem. Educ. Downloaded from pubs.acs.org by UNIV OF SOUTH DAKOTA on 08/24/18. For personal use only.

S Supporting Information *

ABSTRACT: The “Atoms-First” approach has received considerable attention in the chemical education community over the past few years as an alternative to the standard reaction-based two-semester General Chemistry curriculum. The Atoms-First model emphasizes the electronic structure of the atom as a means to explain and rationalize chemical reactions and stoichiometry, which are then covered at the end of the first semester. The current study analyzes the results of switching from a traditional reaction-based curriculum to an Atoms-First approach in a two-semester General Chemistry course with regards to student performance on standardized American Chemical Society (ACS) exams. The study evaluated roughly 600 students over three years of classes, and found that the outcomes were generally favorable for topics related to atomic and molecular structure. A comparison of the two approaches and suggestions for implementation of the Atoms-First approach are also included. KEYWORDS: First-Year Undergraduate/General, Testing/Assessment, Atomic Properties/Structure, Reactions, Laboratory Management, Curriculum

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INTRODUCTION The goals, scope, and material composition of the General Chemistry curriculum have been subject to consistent debate almost since its inception.1 Over time, the curriculum has morphed from a primarily descriptive inorganic chemistry course to a more theory-laden, physical chemistry based course which relies heavily on mathematical problem solving.1 On the basis of growing concerns over the composition of the curriculum, the Task Force on the General Chemistry Curriculum of the American Chemical Society (ACS) put forth recommendations for alterations to the General Chemistry curriculum in an attempt to steer the conversation toward more positive outcomes for the students, faculty, and society.2,3 Since then, efforts have been undertaken to develop and implement pedagogical innovations (e.g., POGIL) and curricular changes (e.g., CLUE, Chemical Thinking (CT)) to improve outcomes in General Chemistry courses.4−8 One of the most prominent developments is the advent of the socalled “Atoms-First” approach (AA), which has attracted significant attention in the chemical education discipline over the past few years.9 This interest has culminated in a parallel line of textbooks published in addition to those already in existence for the Standard Approach (SA), in some cases with the same primary author having both approaches published concurrently.10−17 The organization of the AA, in which the curriculum “builds up” from atomic and molecular structure to chemical reactions, © XXXX American Chemical Society and Division of Chemical Education, Inc.

lends itself well to the pedagogical approach in which the students learn with understanding. According to Bransford, Brown, and Rodney, learning with understanding is a belief that students need to understand what they are learning in lieu of simply memorizing.18 Although there is not currently a consensus on which pedagogical approach is superior, some researchers believe that a combination of approaches may be warranted. Coll and Taylor explained that, due to large class sizes and condensed time frames, alternate approaches to the SA often become problematic.19 They also believed there was “little to be gained by changing this teaching approach” but acknowledged that “effective teaching of challenging conceptions such as atomic structure and chemical bonding” could be improved by the implementation of an alternative constructivist pedagogical approach, where the teacher acts as a facilitator to encourage students to draw upon their background knowledge and develop their own constructs to aid in understanding.20,21 Despite the interest the AA has attracted, few reports have been published regarding the efficacy of the approach, and most anecdotal evidence has been mixed. A recent study conducted by the University of California, Riverside, found that student outcomes dropped during the first year of Received: March 23, 2018 Revised: July 20, 2018

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DOI: 10.1021/acs.jchemed.8b00195 J. Chem. Educ. XXXX, XXX, XXX−XXX

Journal of Chemical Education

Article

adoption of the AA curriculum but recovered (albeit still diminished) in subsequent years, while another at Mississippi State University found the SA to be generally more effective than the AA.22,23 The primary purpose of the study was to determine the possible effect of an AA curriculum on student outcomes, specifically, to test for differences in performance on an ACS exam between students who received instruction under the two approaches, adjusting for students’ aptitude as measured by ACT Science and Math scores. A secondary purpose was to determine whether the difference in performance would be consistent for males and females.

Table 1. Distribution of Students by Instructor, Gender, and Pedagogical Approach Standard Approach (SA) Gender

%

N

%

N

%

N

1

Female Male Total Female Male Total

39.3 60.7 100 40.4 59.6 100

64 99 163 36 53 89

36.3 63.7 100 49.1 50.9 100

69 121 190 82 85 167

37.7 62.3 100 46.1 53.9 100

133 220 353 118 138 256

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RESEARCH METHODOLOGY The present study was conducted at a public university in the state of Tennessee which serves a largely rural population. The student participants in the study were enrolled in a twosemester general education General Chemistry course intended for STEM majors. For the purposes of this study, student data was collected over a period of three years: the last year that the SA was used, and the first two years after the switch to the AA. The three groups (SA, AA1, and AA2) represent different cohorts taking the class during the same term (e.g., fall or spring) over successive academic years. The following data were collected for all students enrolled in the STEM majors General Chemistry course over this period: gender, class when taking the course (e.g., freshman, sophomore, etc.), ACT exam scores (science, math, and cumulative), final course letter grade, and percent score on an ACS standardized exam administered at the end of the second semester. The same full-term General Chemistry exam from the ACS Exams Institute was used for the SA and both semesters of the AA. The exam was administered at the end of the second semester of General Chemistry course and was worth 20% of the students’ final grade in the course. To minimize error due to instructor performance, only sections for which the same instructor taught the second semester course in both the SA and AA were used for the analysis. The SA used Ebbing and Gammon’s 10th edition General Chemistry textbook (published by Cengage) supported by the OWL homework system, while the AA utilized Burdge and Overby’s second edition of ChemistryAtoms First textbook (a McGraw-Hill product) with the Connect and LearnSmart homework systems.

Total

Instructor

2

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Atoms Approach (AA)

DISCUSSION

Comparison of Approaches

The distinction between the SA and AA is most obvious in the first semester of the General Chemistry curriculum, as summarized in Figure 1.11−17,24 The SA introduces qualitative and quantitative aspects of chemical reactions near the beginning of the semester, whereas the AA begins by establishing chemical reactivity through discussion of electronic structure and periodic trends. Thermochemistry and gas laws, the other typical first semester topics, are inserted either between the discussions of structure and reactions or at the end of the course, and their placement tends to vary by textbook rather than approach. One of the main benefits of the AA, and the primary driving force for the instructors in this study adopting the curriculum, is how the material necessarily builds upon itself while minimizing the introduction of factual information before the theoretical aspects underlying the information are discussed. A common example of this is found in the SA, when students are asked to identify the charges of cations and anions of the representative elements based on the group number, despite not having covered the electronic structure of the atom and therefore having no context for why the characteristic ions are formed. In contrast, the AA is an example of a “spiral” curriculum, in which the content continually calls back to previously covered material, which links the concepts and intrinsically reviews the underlying concepts as the semester progresses.25 A significant drawback of the AA is that chemical reactions and stoichiometry, cornerstone topics of a first-semester General Chemistry curriculum, are not covered until toward the end of the semester. This can be particularly important with regards to the laboratory, for those programs that prioritize the connection between lecture and lab, especially if the laboratory curriculum relies heavily on writing chemical equations and observing chemical reactions. Some “AtomsFirst” textbooks introduce the concept of molar mass (for elements) and the mole earlier in the curriculum than would normally be expected for the sake of the laboratory curriculum, but even with this adjustment, most of the classic laboratory experiments (e.g., stoichiometry, limiting reactant, titrations) can wind up crammed into the end of the semester.

Statistical Analysis

The sample consisted of a total of 609 students from six semesters over the course of three calendar years. Of the 609, 41.4% (N = 252) received instruction using the SA, and 58.6% (N = 357) received instruction using the AA. The analysis used data for two instructors who taught using both instructional strategies. Table 1 shows the distribution of students by instructor, gender, and pedagogical approach. The sample of 609 students were from 31 academic majors, which were reclassified into four broad categories of Engineering, Sciences, Pre-Professional (students pursuing careers in the medical/health services fields other than nursing), and Other majors for the purposes of the analysis. A majority of students were freshmen, and so the categories of sophomore, junior, and senior were combined into “Other”. Further breakdowns of the student population are presented in Appendices 1 and 2 in the Supporting Information.

Results

Student results are summarized in Figure 2 for the last semester of the SA (N = 246), the first semester of the AA (AA1, N = 199), and the second semester of the AA (AA2, N = 162). Students with incomplete records (missing ACT science and math scores, which were used as covariates) were not included in the analysis. A one-way multivariate analysis of B



Article

Figure 1. Comparison of content organization in the SA (left, from Ebbing and Gammon) and AA (right, from Burdge and Overby). Adapted with permission from ref 16, Copyright 2013, Cengage Learning, and ref 5, Copyright 2014, McGraw-Hill, respectively. † indicates gas laws can be found either in this position (interchangeably with thermochemistry) or at the end of the curriculum depending on the particular text. ‡ indicates mass/ mol/atom conversions are included here for the benefit of the laboratory curriculum.

showed improvement between the first and second semesters of the AA. It is for this reason that Table 2 compares the outcomes of the SA with the second semester of the AA rather than the first. Table 2 shows a general increase in retention of topics covered earlier in the AA and a decrease in success in material covered later in the semester relative to the SA. Broadly, this tends to suggest that student success is linked with the amount of time students have to interact with the material, rather than the fundamental nature of the approach.

variance (MANOVA) was conducted to determine student success differences between the SA and the AA2. MANOVA results revealed significant differences between the two approaches on the dependents’ variables, Wilk’s Λ = 0.786, F(8, 399) = 13.57, p < 0.001, multivariate η2 = 0.214. Table 2 contains a breakdown of student success rates on each overall topic on the ACS exam for the last semester of the SA and the second semester of the AA. As shown in Figure 2, the initial results for student success under the AA showed immediate improvement for topics such as Atoms and Subatomic Particles, Electronic Structure, and Molecular Structure; however, success rates on the topics of Chemical Reactions and Thermochemistry dipped slightly during the first semester in which the AA was initiated before rebounding slightly in the second semester. This rebound is consistent with the findings of the UCR study, and can likely be attributed, at least in part, to the unfamiliarity the instructors had with the structure of the new course during the first semester of implementation.22 All considered topics

Test of Mean Differences

The purpose of the study was to determine whether there were differences in student performance on the ACS exam by instructional method, controlling for aptitude using math and science ACT subscores. A secondary purpose was to test to see if there was a significant interaction between pedagogical approach and gender. A two-way analysis of covariance (ANCOVA) was conducted to address these purposes. C



Article

ANCOVA was conducted to determine group differences in the mean ACS scores between students who received instruction using the AA versus those who received instruction using the SA, adjusting for aptitude. Gender was also used as a factor in the analysis. There was a significant difference in achievement between the two instructional approaches, albeit the amount of variance in ACS scores explained by instructional strategy was relatively small, less than 2%: F(1,550) = 6.48, p < 0.05, partial η2 = 0.012. Results of the ANCOVA are presented in Table 3. The interaction between approach and gender was not statistically significant, F(1,550) = 0.007, p > 0.05, making the main effects more easily interpretable. The estimated marginal means are presented in Table 4. Table 4. Estimated Marginal Means by Pedagogical Approach and Gender Figure 2. Comparison of student percent success rates (percent of correct responses) on topics on an ACS standard exam for the last semester of the SA and the first and second semester of AA (AA1 and AA2, respectively) for both instructors combined.

Pedagogical Approach Standard Approach

Table 2. Comparison of Student Results for the Last Semester of the SA and Most Recent Semester of AA, AA2

Atoms Approach

Student Success Rate (%) Topic on ACS Standard Exam

AA2

SA

ΔAA2 − SA

Atoms and Subatomic Particles Electronic Structure Compounds Molecular Structure and Bonding Chemical Reactions Thermochemistry Gases

76.75 53.09 65.43 60.49 66.89 64.69 62.35

69.51 39.02 65.14 46.34 70.47 68.46 61.38

7.24a 14.07b 0.29 14.15b −3.58 −3.77 0.97

95% CI Lower Bound

95% CI Upper Bound

Gender

Mean

Std Error

Female, N = 97 Male, N = 136 Female, N = 144 Male, N = 179

56.83

1.46

53.97

59.70

58.34

1.23

55.92

60.75

59.89

1.20

57.54

62.25

61.60

1.08

59.49

63.71

Though the interaction between gender and approach was not statistically significant, both males and females tended to perform better under the AA compared with the SA. Regardless of pedagogical approach, males tended to perform slightly higher than females. The 95% confidence intervals for the two genders for both approaches overlap, confirming the lack of statistical significance in the difference between males and females.

a

p < 0.05. bp < 0.01.

Suggestions for Implementation of AA

A crucial assumption of ANCOVA is the homogeneity of regression slopes. This assumption was tested for both the ACT Math and Science subscores by evaluating the significance of the highest interaction between each covariate and the independent variables. The assumption was met in both instances: ACT Math, F(1,549) = 1.25, p > 0.05, and ACT Science F(1,549) = 2.45, p > 0.05. One can be reasonably confident that both covariates make a uniform adjustment of the dependent variable scores for each of the subgroup scores so that the groups are equivalent with respect to student aptitude. Levene’s test of homogeneity of variances showed that the groups were homogeneous in terms of error variances, F(3,552) = 0.931, p > 0.05.

On the basis of the observed results, the AA is an effective way to improve student performance, but only in certain content areas. While there were significant gains noted in the material covered earlier in the semester related to electronic and molecular structure, these were at least partially counterbalanced by losses in retention of material that was pushed later in the semester, specifically chemical reactions and thermochemistry. One of the recommendations put forth by the Task Force on the General Chemistry Curriculum of the American Society was that curricula be customized to the target audience.2 Therefore, adoption of the AA would be recommended for programs whose goals are to provide a

Table 3. ANCOVA Summary Table Source

Sum of Squares

df

MS

F

Siga

Partial η2

ACT Science ACT Math Approach Gender Approach × Gender Error Total

4495.978 16,962.357 1324.227 330.443 1.355 112,482.707 2,154,001.097

1 1 1 1 1 550 556

4495.978 16962.357 1324.227 330.443 1.355 204.514

21.984 82.940 6.475 1.616 0.007

0.000 0.000 0.011 0.204 0.935

0.038 0.131 0.012 0.003 0.000

Significant at the 0.05 α level.

a

D



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fundamental basis in the microscopic structure of chemical substances rather than a more thorough experience in the macroscopic outcomes of chemical reactions. Implementation of the AA from the SA requires a significant overhaul of the laboratory curriculum for those programs who wish to align their lecture material with the lab exercises. Depending on the technology available, instructors can incorporate experiments relating to spectroscopy in the front part of the curriculum, which corresponds well to the AA’s emphasis on the electronic structure of the atom as a vehicle for chemical reactivity. Spectroscopy experiments can be very interesting to the students as they utilize modern technology, and often have eye-catching visual aspects which can promote student interest in the course. The first half of the lab curriculum can also be utilized for exercises intended to develop the scientific method and/or inquiry-based experiments, though this could be challenging for some first-year students with little to no experience in a laboratory setting. Examples of established laboratory curricula utilized at the institution where the study was conducted for both approaches are given in Table 5.

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Standard Approach

Atoms-First Approach

1 2 3 4 5 6 7 8 9 10

Physical measurement Calibration Stoichiometry Limiting reactant Aqueous reactions Acid−base titration Gas laws Calorimetry Emission spectra VSEPR exercise

Physical measurement Calibration Emission spectra Emission spectra II Nomenclature exercise VSEPR exercise Stoichiometry Limiting reactant Acid−base titration Calorimetry

*E-mail: [email protected]. ORCID

Chad E. Rezsnyak: 0000-0003-2712-7354 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS IRB approval was secured for this study. The authors would like to thank Amanda Carroll, Daniel Swartling, Wathsala Medawala, and Kathy Rust for providing student data for consideration to be used in the analysis; Steven Seiler for his guidance in securing IRB approval; and Kristen Murphy for her assistance in reporting and interpreting ACS exam results.

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REFERENCES

(1) Lloyd, B. W. A review of curricular changes in the general chemistry course during the twentieth century. J. Chem. Educ. 1992, 69 (8), 633. (2) Lloyd, B. W.; Spencer, J. N. The Forum: New Directions for General Chemistry: Recommendations of the Task Force on the General Chemistry Curriculum. J. Chem. Educ. 1994, 71 (3), 206. (3) Gillespie, R. J. What is Wrong with the General Chemistry Course? J. Chem. Educ. 1991, 68 (3), 192. (4) Moog, R. S.; Creegan, F. J.; Hanson, D. M.; Spencer, J. N.; Atraumanis, A.; Bunce, D. M. POGIL: Process-Oriented GuidedInquiry Learning. In Chemists’ Guide to Effective Teaching; Pienta, N. J., Cooper, M. M., Greenbowe, T. J., Eds.; Prentice Hall: Upper Saddle River, NJ, 2009; Vol. 2, pp 90−101. (5) Cooper, M.; Klymkowsky, M. Chemistry, Life, the Universe, and Everything: A New Approach to General Chemistry, and a Model for Curriculum Reform. J. Chem. Educ. 2013, 90 (9), 1116−1122. (6) Anthony, S.; Mernitz, H.; Spencer, B.; Gutwill, J.; Kegley, S. E.; Molinaro, M. The ChemLinks and ModularCHEM Consortia: Using Active and Context-Based Learning To Teach Students How Chemistry Is Actually Done. J. Chem. Educ. 1998, 75 (3), 322. (7) Gutwill-Wise, J. P. The Impact of Active and Context-Based Learning in Introductory Chemistry Courses: An Early Evaluation of the Modular Approach. J. Chem. Educ. 2001, 78 (5), 684. (8) Talanquer, V.; Pollard, J. Reforming a Large Foundational Course: Successes and Challenges. J. Chem. Educ. 2017, 94 (12), 1844−1851. (9) Pienta, N. J. How Do We Measure Success in Introductory College Chemistry? J. Chem. Educ. 2017, 94 (3), 265−266. (10) Burdge, J. Chemistry, 3rd ed.; McGraw-Hill: New York, 2014. (11) Burdge, J.; Overby, J. Chemistry Atoms First, 2nd ed.; McGrawHill: New York, 2014. (12) Gilbert, T. R.; Kirss, R. V.; Foster, N.; Davies, G. Chemistry. The Science in Context, 4th ed.; W. W. Norton & Company, Inc.: New York, 2015. (13) Gilbert, T. R.; Kirss, R. V.; Foster, N.; Bretz, S. L. Chemistry An Atoms-Focused Approach; W. W. Norton & Company: New York, 2018. (14) Tro, N. J. Chemistry: Structure and Properties, 1st ed.; Pearson: Upper Saddle River, NJ, 2015. (15) Tro, N. J. Chemistry: A Molecular Approach, 3rd ed.; Pearson: Upper Saddle River, NJ, 2014. (16) Zumdahl, S. S.; Zumdahl, S. A. Chemistry: An Atoms First Approach, 2nd ed.; Cengage Learning: Boston, MA, 2016. (17) Zumdahl, S. S.; Zumdahl, S. A.; DeCoste, D. J. Chemistry, 10th ed.; Cengage Learning: Boston, MA, 2018.

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CONCLUSION The Atoms-First approach provides a presentation of material for the first semester General Chemistry curriculum that uses submicroscopic structure to explain macroscopic properties of chemical substances and reactions. The AA had a statistically significantly higher average than the SA on student outcomes overall, which was independent of student aptitude and gender. The approach is most effective with regard to structure and bonding topics, but at the expense of the more quantitative aspects involving reaction stoichiometry and thermochemistry. Adoption of the AA generally requires an overhaul of the laboratory curriculum if it is to be symbiotic with the lecture material. These challenges are significant, though surmountable, if the instructors are motivated and their interests align with the supported outcomes. One important point to consider is that the change in curriculum toward AA does not harm the students in terms of their academic outcomes. In fact, it may be beneficial, although in the present study, the effect size is quite small, less than 2%.

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AUTHOR INFORMATION

Corresponding Author

Table 5. Comparison of Laboratory Curricula Experiments by Approach Expt

Additional student classification information (PDF, DOCX)

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.8b00195. E



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(18) How People Learn: Brain, Mind, Experience, and School, expanded ed.; The National Academies Press: Washington, DC, 2000; p 384. (19) Coll, R. K.; Taylor, T. G. N. Using Constructivism to Inform Tertiary Chemistry Pedagogy. Chem. Educ. Res. Pract. 2001, 2 (3), 215−226. (20) Bodner, G. M. Constructivism: A theory of knowledge. J. Chem. Educ. 1986, 63 (10), 873. (21) Resnick, L. B. Mathematics and Science Learning: A New Conception. Science 1983, 220 (4596), 477−478. (22) Esterling, K. M.; Bartels, L. Atoms-First Curriculum: A Comparison of Student Success in General Chemistry. J. Chem. Educ. 2013, 90 (11), 1433−1436. (23) Hillesheim, C. S. Comparison of Student Success using “Atoms First” Versus “Traditional” Curricula. Ph.D. Dissertation, Mississippi State University, Mississippi State, MS, 2016. http://sun.library. msstate.edu/ETD-db/theses/available/etd-07082016-165944/ (accessed Jul 2018). (24) Ebbing, D. D.; Gammon, S. D. General Chemistry, 10th ed.; Cengage Learning: Belmont, CA, 2013. (25) Bruner, J. S. The Process of Education; Harvard University Press: Cambridge, MA, 1960.

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Impact of an Atoms-First Approach on Student ... - ACS Publications

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